This is a fantastic book. There are many varieties of puzzles, including
some types that I’ve never seen before. Also, the beautifully designed
puzzles are great. Often puzzles of the same type target different
solving ideas or have varied cool themes.

This book is more than a bunch of puzzles; it also contains poetic
stories about puzzle histories and Japanese puzzle designers. Fantastic
puzzles together with a human touch: this might be my favorite puzzle
book.

I present two puzzles from the book. The puzzle type is called Wolf and Sheep Slitherlink.
The Slitherlink is a famous puzzle type with the goal of connecting
some of the neighboring dots into a single non-self-intersecting loop. A
number inside a small square cell indicates how many sides of the
square are part of the loop. Wolf and Sheep Slitherlink is a variation of Slitherlink in which all sheep should be kept inside the fence (loop) and all the wolves outside.

Ignore the numbers in the title as they just indicate the order number
of Wolf and Sheep Slitherlink puzzles in the book. The number of ninja
heads shows the level of difficulty. (The hardest puzzles in the book
have four heads.) The difficulty is followed by the name of the puzzle
master who designed the puzzle.

The first puzzle above is slightly easier than the second. I like the
themes of these two puzzles. In the first one, only one cell—lonely
wolf—marks the relationship to the fence. In the second one, the wolf in
the center—who needs to be outside the fence—is surrounded by a circle
of sheep who are in turn surrounded by a circle of wolves.